2.3.6. Disintegration Time

Six tablets from each batch were subjected to disintegration test in a freshly prepared distilled water and phosphate buffer (pH 7.2) at 37 ± 0.5 °C using disintegration test apparatus Sotax DT-2 (Sotax Gmbh) with 900 mL of distilled water without disk. The disintegration times were taken and the mean disintegration time was calculated [14,21,22].

Wetting time: A piece of tissue paper of 10 cm diameter was placed in a 10 cm diameter Petri dish containing 10 mL of water. A tablet was put on the paper. A time required for water to reach upper surface of the tablet was noted as the wetting time.

Water absorption ratio test was done following the same procedure as for the wetting time. A tablet was weighed and put on the paper in a Petri dish. When water reached the top surface of the tablet and it was completely wet, the tablet was weighed again. Water absorption ratio (R) was calculated according to Equation (5):

where:

V_a—tablet weight before water absorption;

V_b—tablet weight after water absorption.

In vitro drug release: In vitro meloxicam release of from orally disintegrating tablets was determined using USP Dissolution Apparatus (Paddle type, model, Sotax AT7, Sotax Gmbh) [28,29,30]. A volume of 700 mL of phosphate buffer (pH 7.2), a dissolution medium at 37 ± 0.5 °C, was added to the dishes of the apparatus. Blade rotation speed 50 rpm. Samples were taken after 2; 4; 6; 8; and 10 min of testing. Sample volume was 5 mL. The volume of the taken samples was replaced by fresh dissolution medium. The samples were filtrated before chromatographic analysis. The analysis of samples was performed using high performance liquid chromatography (HPLC) method. A Waters 2695 chromatography system (Waters, Milford, MA, USA) equipped with Waters 996 PDA detector of absorbance at 350 nm was used.

In the oral cavity, the pH is maintained near neutrality (6.7–7.3) by saliva [31]. The dissolution test of the tablets was performed in a phosphate buffer solution with a pH of 7.2. The used medium did not affect wetting time, solution absorption, and disintegration time of meloxicam tablets.

Stability testing: Accelerated stability testing was performed for 6 months as per ICH guidelines [32]. The optimized formulations were kept at 40 ± 2 °C and 75 ± 5% RH. Physical changes, tablet hardness, and disintegration time changes were assessed every 3 months.